1. Field of the Invention
The invention relates to a semiconductor device having a capacitor element.
2. Description of the Related Art
In order to reduce variation of a voltage level by influence of electromagnetic noise to prevent malfunction of a semiconductor die, a capacitor element called a bypass capacitor has been mounted on a terminal (a source terminal or a ground terminal) of a semiconductor die conventionally.
For example, Japanese Patent Application Publication No. Hei 05-021698 discloses a semiconductor device in which a semiconductor die and an external capacitor element called a die capacitor are mounted on the same substrate and packaged in a die form as a whole.
Japanese Patent Application Publication No. 2000-349238 discloses a semiconductor device formed with a capacitor element functioning as a bypass capacitor by using a multilayered wiring layer on a semiconductor substrate and an interlayer insulation film between these.
However, although the structure using the external capacitor element as described in Japanese Patent Application publication No. Hei 05-021698 obtains large capacitance in the capacitor element, it needs a space for mounting the capacitor element on the substrate. Therefore, it is difficult to reduce the size of the device as a whole.
Furthermore, since recent semiconductor dies operate fast, high frequency (frequency of several hundreds MHz or more) electromagnetic noise is likely to increase by a high speed switching operation of a transistor to degrade operation characteristics. Therefore, a technique of effectively removing such electromagnetic noise is desired.
One method of reducing influence of electromagnetic noise is that a semiconductor die and a capacitor element are formed adjacent as much as possible to reduce the impedance and inductance of a wiring (a source wiring or a ground wiring) connecting these. However, the wiring may be extended long for a layout design in some cases, and when the semiconductor die and the capacitor element are individual components there is a limitation on the adjacent formation of these.
As described above, the structure having the external capacitor element has a problem of difficulty in realizing both the size reduction of the semiconductor device and the reduction of an influence of electromagnetic noise.
On the other hand, the conventional structure having the capacitor element formed in the same semiconductor device as described in Japanese Patent Application publication No. 2000-349238 may reduce the impedance and inductance of the wiring more than the case using the external capacitor element, but it requires a large area for obtaining enough capacitance to effectively remove high frequency electromagnetic noise.
Therefore, this has a problem of difficulty in size reduction of the semiconductor device since other functional elements (e.g. a driver circuit or a logic circuit formed by a transistor or the like, wirings connected to these, or the like) other than the capacitor element are formed on the same semiconductor substrate.
Therefore, the invention provides a semiconductor device which has a capacitor element therein to achieve size reduction of the device, the capacitor element having larger capacitance than conventional. Such a semiconductor device reduces an influence of electromagnetic noise.